pump question

cooperstone · Jun 27, 2009

I installed a new, 1/2 HP SHUR-DRI shallow well pump. The wiring is done to specs. and above. I can run the pump for a while, and then it will just shut off. After a few minutes, it will work again. I am pumping from a pond into a pressure tank.

I think it may be overheating. There is a sign on the pump that say thermally controlled, so I thought maybe it was a safety device of some kind, but the manufacturer does not mention this in the instructions.

Has anyone else had this problem? Any thoughts from the experts?

Thanks.

Speedbump · Jun 27, 2009

I think Shur Dri is an offshoot of the Myers pump. Similar to the Water Ace. It has a cheap motor on it (the cheapest). Either you have it wired for 230 volts and your feeding it 115 volts. Or, your trying to run it on an extension cord or wiring that is too small to carry the load or both.

Even though they put a junkie motor on these pumps, it should work for a year or so before self destructing. If it doesn't work at all, then it could be a manufacturers defect. Most pumps if they work out of the box, they are going to keep working until planned obsolescence gets to them.

Sponsor · 2022-01-29T12:20:58-0800

cooperstone · Jun 27, 2009

Thanks. My wiring is correct according to manufacturer specs. If I take this one back, what is a name brand you would recommend?

Thatguy · Jun 27, 2009

not so fast

Check that the voltage matches the nameplate and then check that the current draw is within spec's.
A clamp-on ammeter will pay for itself the first time you use it to correctly diagnose a problem like this.
A 1/2 hp @115v motor
http://books.google.com/books?id=DD...X&oi=book_result&ct=result&resnum=4#PPA122,M1
will draw 9.8A (Table 9.2) to ~4A.

cooperstone · Jun 27, 2009

I'm running a 220amp, 30 amp double-pole breaker with #10 wire. The pump will run for an hour or more, cut off for about 20 minutes, and then come back on. I'm almost 100% sure it's not a wiring problem.

Thatguy · Jun 27, 2009

cooperstone said:
I'm running a 220amp, 30 amp double-pole breaker with #10 wire. The pump will run for an hour or more, cut off for about 20 minutes, and then come back on.

Your current draw should then be 2 to 5A at 220v.

First make sure this is not normal behavior-if it's not cutting off due to some pressure setpoint being reached, it sounds like a thermal overload switch cycling inside the motor, but the current draw should give you a clue.

Less likely is that a high resistance bad connection is causing a lower voltage at the motor.

There probably shouldn't be more than a 5% voltage drop from the source end of the wire to the destination (motor) end, at normal current draw.
How long is the wire? 5% of 220v = 11v, and at 5 amps you'd need 1100' (2200' conductor length) of #10 to get this much drop.

cooperstone · Jun 27, 2009

Thanks. I'll measure both ends to see what I get. Really appreciate your help.

Gary Slusser · Jun 27, 2009

Man #10, how far did you have to run electric?

How much water are you getting?

If you aren't getting what you think you should, maybe the pump's inlet in the pond is blocked. If the pump is out in the sun with high air temps, you might want to shade it.

cooperstone · Jun 27, 2009

We had no voltage drop between the elec. source and the cut-off... but... we found a drop between the cut-off and the pump. Upon further inspection, we found a ground wire that had come loose. After reconnecting the ground wire, we had no voltage drop... of course.

I wouldn't have thought the pump would have worked at all without the ground wire being connected! I hope we didn't burn up the pump. I guess that's why there is a sign on the pump that says "Thermally controlled."

I cannot thank you enough for your help. Without checking the voltage drop, we would have never found the problem.

Thanks again!!

Gary Slusser · Jun 27, 2009

We were typing at the same time so check my reply above.

Since it got so hot, there's a good change you melted the impeller etc..

cooperstone · Jun 27, 2009

We ran the wire approx. 450'. We have an uninsulated well-house with a metal roof. The temperature today is 105. It's been in the low 100's for the past several days, and no relief in sight. We're in Central Texas, setting heat records.

We don't have a pressure problem. We used 1 1/4" pvc so volume is fine.

Thatguy · Jun 27, 2009

cooperstone said:
we found a ground wire that had come loose. After reconnecting the ground wire, we had no voltage drop... of course.
1
I wouldn't have thought the pump would have worked at all without the ground wire being connected!
2

1 The ground wire is for safety; it shouldn't affect your problem.
2 It shouldn't make any difference.

If your problem has gone away, I have no idea why!

cooperstone · Jun 27, 2009

Actually, I shouldn't have called it a ground wire. It is actually the the neutral or third wire. There is no "ground" wire.

Speedbump · Jun 29, 2009

There is no neutral in a 230 volt single phase hookup. There are two hots. Period. The third wire should be a ground. Either green or bare. It should be connected to the frame of the motor.

The more water the pump is moving the more amps it is pulling. If you deadhead the pump at it's max pressure by shutting off the main valve, the amps will be the same as if the pump weren't connected to the motor.

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